Tamping plug



M. E. BECK TAMPING PLUG Aug. 9, 1966 Filed March 9, 1964 FIG.?

INVENTOR. MARLIN E. BECK ATTORNEYS United States Patent 3,264,992 TAMPING PLUG Marlin E. Beck, 13 S. Filbert St, Allentown, Pa. Filed Mar. 9, 1964, Ser. No. 350,403

' 8 Claims. (Cl. 102-30) This invention relates to a tamping or blasting plug and to a blasting plug assembly comprising a cooperating pair of tamping plugs or wedges characterized in that one is substantially identical With and the complement of the other and each expandable cooperatively with the other.

In blasting rock, coal and other minerals, and the like, the practice is to drill holes into the material to be blasted, to charge the holes with an explosive, such as dynamite, and to detonate the explosive charge using an electric current or a combustible fuse. Generally, it is the practice to increase the efiicacy of the explosive charge by stemming the charged hole with a tamping means, usually comprised of earth, clay or sand, or a combination of these. This type of tamping has its disadvantages in that sometimes it lets go prematurely whereby some of the explosive force is lost through the opening of the hole.

In order to insure the full use of the explosive, the trend recently has been towards the use of blasting plugs of the expandable type such that under the force of the explosive, the plug tends to expand and tighten its grip on the cylindrical wall of the drill hole. In this connection, a solid rubber plug has been proposed, but this had its disadvantages in that the explosion would tend to break the rubber into relatively large pieces which are dangerous when blown out of the hole. Moreover, the charring of the rubber generally results in a disagreeable odor which tends to discourage its use.

Another proposal is to use a cylinder formed of folded asbestos fabric which is expandable by a wooden wedge, or other similar material. In this case, the wooden wedge tends to produce dangerous flying particles, and the asbestos fabric tends to disintegrate into a fine white dust which is harmful to the human lungs. A still further proposal involves using an expandable female plug having a tapered recess into which is fitted a complementary tapered male plug. By tamping the male plug in position, the female plug expands and wedges itself in the drill hole.

The disadvantage of such plug assemblies is that two different plug elements are required to be made which adds to the cost of the assembly, and, moreover, only one of the elements is expandable relative to the other.

It is the object of this invention to provide a novel blasting plug element characterized in that two of the same elements can be employed in the construction of an expandable blasting plug assembly.

Another object is to provide a blasting plug element such that when two of the same elements are fitted together to form a blasting plug assembly, each is expandable cooperatively with the other whereby the plug is capable of double action when a force is applied to one or the other or both of the plug elements making up the blasting plug assembly. 7

A still further object is to provide a blasting plug element and assembly capable of sealing holes of irregular shape or out of round.

As a preferred embodiment, I provide a plug made of light weight deformable material which does not give off an obnoxious odor when burned and which does not irritate the eyes.

As an additional object, I provide a plug element which is easy and economical to manufacture.

These and other objects will more clearly appear from the following description and the accompanying drawing, wherein:

FIGS. 1 to 3 are top, side and front views, respectively,

of a preferred embodiment of a blasting plug element; FIG. 4 is a partial section of the plug of FIGS. 1 to 3 as taken along line 4-4 of FIG. 2 as seen in the direction of the arrows; FIG. 5 is illustrative of one embodiment of the blastmg plug assembly using a pair of blasting plug elements shown in FIGS. 1 to 3;

FIG. 6 is a cross section of the assembly taken along line 6-6 of FIG. 5; and

FIG. 7 is a diagrammatic section through a blasting hole showing the positioning of the blasting plug assembly.

Referring now to the drawing, FIGS. 1 to 4 are illustrative of one embodiment of the blasting plug element provided by the invention comprising broad-1y a wedge of deformable material, for example expanded polystyrene, having a head portion and a plurality of spaced legs extending longitudinally of the head portion. The embodiment shown in the drawing is illustrative of a twolegged wedge comprising a head portion 10 having a spherical surface 11 at its end adapted to receive force and spread it evenly over the head of the wedge. Two

legs 12 and 13 project or extend longitudinally of the head portion, the legs being preferably bevelled inwardly thereof as at 14, 15 and 16 of leg 13, and 14a, 15a and 16a of leg 12. The two legs are shown apart, that is diametrically opposed to each other, with diametrically opposed spaces 17 and 18 between said legs. The size of each of the legs is larger than the dimensions of the diametrically opposed faces so that when the legs of another element are inserted into the spaces between the host plug, stress is applied to the legs of the host plug. The

bevelled edges are preferred in that they provide riding faces on each side of the spaces against which a complementary leg of another blasting plug element of substan-.

tially the same configuration can bear when two elements of the same configuration are wedged together as shown in FIGS. 5 and 6.

Referring to FIG. 5, two plug elements are shown wedged together with the legs of wedge 20 fitted into the smaller diametrically opposed spaces of wedge 21, the wedging action resulting in all four legs of the blasting plug assembly spreading transversely of the longitudinal axis of the assembly. In FIG. 5, leg 22 and its diametrically opposed leg 23 (note FIG. 6) are shown forced into the opposed complementary spaces of wedge 21 whose legs 24, 25 are shown riding the bevelled faces of legs 22 and 23 in the opposed spaces of wedge 20. Because the spaces between the legs are smaller in dimension than the legs, all four legs are caused to spread transversely as the plug elements are pushed together such that at least the central portion of the assembled wedges is caused to expand diametrically as depicted in the cross section of FIG. 6 which shows the extent of expansion relative to the dotted circle 26 which represents the diameter of the head portion of each of the elements.

The advantage of the foregoing configuration is that instead of only one element of the plug assembly expanding under the application of the force, bot-h expand simultaneously, whether the force is applied on one end or the other; to this extent, they are double acting. While two legs are shown in the embodiment illustrated in the drawing, it will be appreciated that three or four legs may be employed provided they are substantially evenly spaced apart so that the elements making up a plug assembly are substantially identical so that one is a complement of the other. This is an important consideration from an economic viewpoint.

The manner in which the plug assembly is used in a blasting hole is depicted in FIG. 7 which shows an array of explosive elements 27 connected to electrical lead wire 28 emerging from the hole. Assembled plug 29 is shown comprising plug elements 30 and 31 locked in position by a ramming tool causing element 30 to wedge into element 31 whereby all four legs of the assembled plug are caused to spread transversely against the cylindrical wall of the hole. As will be apparent, when the explosive is detonated the force applied to the end of the plug element 30 serves to further expand the assembly against the wall before the heat of the explosion begins to disintegrate the plug. Up to that point, the force of the explosion is confined within the drill hole whereby substantially its full effect is utilized at the bottom of the hole.

As has been stated hereinbefore, the material from which the plug elements may be produced may comprise any material having deformable characteristics. I prefer to use a flexible foamed or cellular plastic such as polystyrene. However, other cellular plastics may be employed so long as they are deformable and expandable When employed as a plug. Examples of other cellular plastics are flexible polyurethane foam, flexible cellular polyethylene, flexible cellular polypropylene, flexible silicone foams and the like. Generally, the densities of such foams for my purposes may range from about 1.5 to as high as or pounds per cubic foot. The advantages of using cellular plastics is that the blasting plug element can be molded to the desired shape easily by pouring an expanding mixture of the plastic into a mold and allowing it to expand and cure while taking on the internal config-- uration of the mold.

The advantages of using the expandable plug assembly of my invention are: it will seal holes of irregular shapes or out of round; the deformable material by virtue of the spreading of the legs will deform to suit the configuration of the hole or cavity when pressure is applied; by using expanded cellular polystyrene as the preferred material, obnoxious odors are minimized as a result of burning of the plug and, moreover, polystyrene tends to be fire retardant; the use of cellular plastic material has the advantage that short circuits are avoided between lead wires of the blasting cap; by using low density expanded cellular polystyrene, for example a low density of 1.5 to 10 pounds per cubic foot, the material blown out of the hole will not be dangerous; the plug element requiring only one part is economical to manufacture; and plug elements made of flexible expanded cellular plastics will withstand roug-h handling and wide variations in temperature. In addition, such cellular plastic materials as polystyrene can be stored indefinitely; are not affected by humidity; are water resistant; are light weight in construction; are easy to position in the drill hole; either end of the assembly can be placed in the drill hole; shipping presents no problem; plugs can stand prolonged exposure to the elements and the assembly has a dual action in that both elements expand simultaneously when force is applied to one or the other end of the assembly.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and the appended claims.

What is claimed is:

1. A pair of blasting plug elements, each of said elements comprising an expandable wedge of deformable 4 material, each of said wedges being a complement of the other and having a head portion and a plurality of spaced legs extending longitudinally of said head portion with complementary spaces between said legs, each of the legs of one of said wedges being capable of being wedged into a corresponding space of the other wedge.

2. The pair of blasting plug elements of claim 1, wherein the deformable material is expanded plastic.

3. A blasting plug assembly comprising a pair of expandable wedges of deformable material, each of said wedges being a complement of the other and having a head portion and a plurality of spaced legs extending longitudinally of said head portion with complementary spaces between said legs, each of the legs of one of said wedges being wedged into a corresponding space of the other wedge.

4. A blasting plug assembly comprising a pair of expandable wedges of deformable plastic material, each of said wedges being a complement of the other and having a head portion and a plurality of spaced legs extending longitudinally of said head portion with complementary spaces between said legs, each of the legs of one of said wedges being wedged into a corresponding space of the other wedge.

5. A blasting plug assembly comprising a pair of expandable wedges of deformable expanded plastic material, each of said wedges being a complement of the other and having a head portion and a plurality of spaced tapered legs extending longitudinally of said head portion with complementary spaces between said legs, each of the tapered legs of one of said wedges being wedged into a corresponding space of the other wedge.

6. A blasting plug assembly comprising, a pair of expandable wedges of deformable expanded polystyrene, each of said wedges being a complement of the other and having a head portion and a pair of diametrically opposed tapered legs extending longitudinally of said head portion with complementary spaces between said legs, each of the tapered legs of one of said wedges being wedged into a corresponding space of the other Wedge.

7. A blasting plug assembly comprising a pair of expandable wedges of deformable expanded plastic, each of said wedges being a complement of the other and having a head portion and a pair of diametrically opposed tapered legs extending longitudinally of said head ortion with diametrically opposed complementary spaces between said legs, the size of each space being smaller than each of the opposed legs, each of said legs being bevelled inwardly on each side thereof, each of the legs of one of said wedges being wedged into a cor-responding space of the other wedge.

8. The blasting plug assembly of claim 7 wherein the expanded plastic is polystyrene.

References Cited by the Examiner UNITED STATES PATENTS 588,784 8/1897 Steffens 215-52 2,710,027 6/1955 Husgen et al. 138-89 3,126,827 3/1964 McReynolds l0230 BENJAMIN A. BORCHELT, Primary Examiner.

R. V. LOTTMANN, Assistant Examiner. 

1. A PAIR OF BLASTIN G PLUG ELEMENTS, EACH OF SAID ELEMENTS COMPRISING AN EXPANDABLE WEDGE OF DEFORMABLE MATERIAL, EACH OF SAID WEDGES BEING A COMPLEMENT OF THE OTHER AND HAVING A HEAD PORTION AND A PLURALITY OF SPACED LEGS EXTENDING LONGITUDINALLY OF SAID HEAD PORTION WITH COMPLEMENTARY SPACES BETWEEN SAID LEGS, OF THE LEGS OF ONE OF SAID WEDGES BEING CAPABLE OF BEING WEDGE INTO A CORRESPONDING SPACE OF THE OTHER WEDGE. 